Flash Communication:\nTi-Catalyzed “Interrupted”\nCascading Hydroamination of 1,6- and 1,7-En-ynes

Herein, we report a new hydroaminative cyclization for\n1,6- and\n1,7-en-ynes using a simple Ti imido precatalyst, [py<sub>2</sub>TiCl<sub>2</sub>(NPh)]<sub>2</sub>. The well-known Ti imido + alkyne [2 +\n2] azatitanacyclobutadiene cycloadduct intermediate can be further\nintercepted via insertion by tethered alkenes, followed by protonolysis\nof the resultant metallacycle to yield α-carbocyclic imine products\nthrough cascading C–N and C–C bond formation.